The present invention concerns the field of intraoral sensors for taking x-ray images.
The first electronic intraoral x-ray image sensors have been commercialized approximately in 1990. These sensors are intended to be placed in the mouth of a patient to produce an x-ray image of the teeth and/or the jaw. The sensor typically comprises an electronic image receptor having an active imaging area. The receptor is encapsulated and protected by a housing, which may be composed of plastic and/or metal elements. Image sensors of this type of construction have rapidly gained market share over the traditional method of using photographic film because the electronic x-ray image is immediately available and can be enhanced on a computer using sophisticated imaging software.
Typical dental applications of such image sensors are the acquisition of so-called “periapical” and “bite-wings” images. In order to take a periapical image, the sensor is positioned vertically with its anterior side tightly close to the zone where the tooth apex is located. For bite-wings images, the sensor is positioned with its anterior side deeply inserted into the mouth of the patient to capture both the upper and lower crowns of the teeth. The patient is asked to close his or her mouth as much as possible, thus bringing the lateral side of the sensor in contact with the palatal and lingual surfaces (i.e., the “the ceiling” and “floor”) of the mouth of the patient. It is important that the patient is able to close his or her mouth as much as possible in order to obtain a maximum image area.
U.S. Pat. No. 6,169,781 discloses an image sensor with an approximately rectangular housing. The anterior side of the housing is rounded in a way that is adapted to the anatomical characteristics of the upper jaw of the average patient. A smoothing or indentation with a relatively large radius is formed on the back side of the housing between a cable connection dome and the anterior side of the housing. The indentation reaches up to the anterior side of the housing so that the housing is thinner at its anterior side than it is at its posterior side.
U.S. Pat. No. 5,691,539 discloses an intraoral sensing device with a rounded, octagonal shaped housing.
U.S. Pat. No. 5,510,623 discloses a solid state CCD image receptor having an octagonal shape. This document also discloses a sensor package with an octagonal shaped housing. The housing comprises a cable connection dome that extends up to the anterior side of the sensor.
The design of a dental image sensor is a difficult task. On the one hand, the inactive rims between the electronic image receptor and the outer side of the housing should be as small as possible, thus allowing to capture as much as possible of the subject of interest within in the active imaging area. The thinner the inactive rim is (mainly with respect to the lateral side for bite-wings images and mainly with respect to the anterior side for periapical images), the more of the subject will be captured within the imaging area. On the other hand, it is important that the sensor has a rounded, comfortable housing so that the patient will cooperate and close his or her mouth around the sensor as much as possible. This is especially important when the patient is a child or tends to overreact or has a marked gag reflex or has an easily irritable oral anatomy.
In solving the above problems, not only the sensor itself must be considered, but also the overall assembly when the sensor is inserted into a holder or positioning device. This whole assembly should easily fit into the patient's mouth, creating as little discomfort or irritation as possible while at the same time allowing the capture of high-quality images of the desired region.